1. Field of the Invention
The present invention relates to a DC commutator motor and an automobile including the same, and particularly, to a DC commutator motor including an upper coil and a lower coil connected in parallel as an armature winding, and an automobile including the same.
2. Description of the Related Art
DC commutator motors, with which high power can be obtained with ease, have been used as, for example, motors for driving hydraulic pumps for vehicles. In recent years, DC commutator motors have also started being used for auxiliary machines of an automobile besides hydraulic pumps in order to reduce fuel consumption of the automobile. The number of DC commutator motors mounted on an automobile is on the increase under such circumstances. To cope with this trend, a reduction in size and weight of a motor should be promoted while its output is maintained. Consequently, an output power volume ratio (a value obtained by dividing the output of a motor by the volume of the motor) demanded of a DC commutator motor to be mounted on an automobile is ever increasing.
There is a DC commutator motor known for each coil constituted by one winding conductor wound in a wave winding (see, for example, JP-2007-151268-A).
Here, the maximum applied voltage of the DC commutator motor is the guaranteed voltage of a battery to be mounted on an automobile, and hence, the output power volume ratio is increased by increasing a current flowing through the DC commutator motor (use of high current). The use of the high current, however, leads to an elevated temperature of the DC commutator motor. Thus, an adequate diameter is selected for the winding conductor to keep the temperature elevation in an allowable range. Particularly, in order to cope with the use of the high current, the winding conductor is designed to have a diameter increased accordingly. Here, winding tension is increased so that the winding conductor fits securely in the inside of a slot provided in an armature.